Vat preparation on invoice basis converted to cash basis

Good morning.

We traditionally prepare vat returns on a basis which best reflects the trading of a vat registered business. We will prepare on either Cash Accounting or Standard listing invoices.

There are some clients typically CIS who benefit cashflow from prodcuing vat returns on a cash basis but due to the delay in information typically CIS certificates this is not always easy so it is easier, and cheaper for client to have us prepare vat returns from sales and purchase invoice analysis.

However my query is can you prepare on a standard vat accounting and convert to cash by simply adjusing for debtors and creditors at quarter end.